Heney alabastbe



(No Model.)

H. ALABASTER & T. GATE-HOUSE.

TELEPHOINIG" TRANSMITTER. N0. 314,30 7. Patented Mar. 24, 1885.

UNITED STATES ATENT OFFICE.

HENRY ALABASTEE, OF SOUTH OROYDON, AND TOM ERNEST GATEHOUSE, OF OAMBERWELL, COUNTY OF SURREY, ENGLAND.

TELEPHONIC TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 314,307, dated March 24, 1885.

Application filed September 20, 1884. (No model.) Patented in England January 11, 1883, N0. 179, and in France July 10,1883,

Nol 156,510.

To all whom it may concern:

Be it known that we, HENRY ALABASTER, of South Oroydon, in the county of Surrey, and ToM ERNEST GATEHOUSE, of Oamberwell,

in the same county, in England, both citizens of Great Britain,haveinvented certain new and useful Improvements in Telephonic Transmitters, (patented also in Great Britain January 11, 1883, No. 179, and in France July 10, 1883,

No. 156,510,) of which the following isaspecification.

Our invention relates to the construction of instruments to receive vocal or acoustic impulses for transmission in a telephonic circuit,

1 technically known as transmitters, and is designed to effect louder and clearer trans mitted articulation, and in the absence of a fixed vibrating diaphragm or tympan to afford an increased sensitiveness, and to avoid the creation of any continued dominant tone or buzz during the use of theinstrument.

Our invention consi. ts of a bridge with an accurately plane and smooth under surface, resting upon and forming electrical contact 2 5 between electrodes, the said electrodes also having accurately plane and smooth upper surfaces, all preferably, but not necessarily, of carbon, the said bridge receiving direct the acousticimpulses through a confined passage such as aspeaking-tube combined therewith.

In order that our invention may be the bettcr understood, we now proceed to describe the same with reference to the drawings hereunto annexed, in which like letters refer to 3 5 like parts throughout the figures.

Figure 1 is a sectional elevation of our device. Fig. 2 is a sectional plan ofsame through a; y of Fig. 1 Fig. 3 is a transverse section through c w of Fig. 2.

0 Two semicircular carbon electrodes, A, and a guide-pin, B, are set on an insulating-base, O, the electrodes A being connected to brass plates D on one side of' the base, which are convenient for connection to the circuit E.

The bottom surfaces of the electrodes may be coated with a deposit of metal, conveniently copper, and connected by a soldered wire to the contact brass plates D. This connection, however, may be made in any suitable manner. Upon these electrodes A rests a carbon bridge, F, perfectly free above and around,

sufficiently thick and rigid to be inflexible in itself, but light enough to be subject to agitation under acoustic impulses received through a confined passage or speaking-tube, G, as a whole in regard to the said electrodes, which agitation is electrically conveyed to the circuit E.

The contact-surfiices of the bridge F and electrodes A are plane and smooth, and the 6 bridge is prevented from dancing off the electrodes or touching the sides of the casing by the guidepin B, set in the insulatingbase and passing through the center of the bridge.

The tube G, through which the acoustic im- 6 5 pulses are received, is conveniently fitted to a cap, H, of any convenient materiahfixed on the casing I; but this cap is not necessarily closed, as it may merely be an open support to the tube. It is only essential that the acous- 7o tic impulses should be made to impinge directly upon the bridge from the mouthof the confined passage or speaking-tube.

The carbon bridge, though shown in the form of a disk, may be a block, or of any other suitable form, and the form of the electrodes may vary accordingly, as may also the form of steady-pin or guide.

We do not claim two electrodes arranged side by side in the same plane and supporting 8o abridge of conducting material; but,

Having now fully described and ascertained the nature and objects of our invention and the manner of its performance, be it known that what we consider novel and useful, and 8 desire to protect by Letters Patent, is-

In a telephonic transmitter, the combina tion which consists of a holder at the end of an acoustictube, two carbon electrodes in the holder, and a bridge resting across the eleco trodes, and so placed in the end of the acoustic tube as to receive upon its back the acoustic impulses transmitted through the tube.

Signed at 6 St.-Dunstans Hill, London, in the county of Middlesex, in England, this 6th 5 day of August, 1884.

HENRY ALABASTER. TOM ERNEST GATEHOUSE.

Witnesses:

FRED CHEEswRIGHr, SAM. P. WILDING. 

